Flat Lens Promise A Revolution In Optics

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Flat Lens The world of optics could soon be revolutionised by the invention of a flat lens that has been made out of paint whitener on a sliver of glass.

The US inventors of the lens have created a flat lens that is just 2mm across and finer than a human hair.

“In my opinion, this technology will be game-changing,” said Federico Capasso of Harvard University, the senior author of the report.

The tiny device can magnify nanoscale objects. It is so powerful that it can give a sharper focus to objects than top-end microscope lenses.

The report on the lens appeared in the journal Science.

Power of metamaterials

The newly created lens is the latest example of the power of metamaterials, whose unique properties are a result of their structure.

Crafted out of a thin layer of transparent quartz coated in millions of tiny pillars that are each just tens of nanometres across and hundreds high, the shapes on the lens are smaller than a thousandth of a millimeter.

Each of the tiny pillars interacts strongly with light, slices up a light beam and remoulds it as the rays pass through the array.

Prof Capasso said that these “metalenses” avoid aberrations that are found in traditional glass optics.

“The quality of our images is actually better than with a state-of-the-art objective lens. I think it is no exaggeration to say that this is potentially revolutionary.”

When compared with the top-end lenses used in research microscopes, the focal spot of the flat lens was found to be typically 30% sharper than its competition.

Revolutionary technology

Prof Capasso said,

“The conventional fabrication of shaped lenses depends on moulding and essentially goes back to 19th Century technology.

“But our lenses, being planar, can be fabricated in the same foundries that make computer chips. So all of a sudden the factories that make integrated circuits can make our lenses.”

Prof Capasso sees the potential uses of the lens in cell phone cameras, mass-produced cameras for quality control in factories, light-weight optics for virtual-reality headsets and even contact lenses.

“We can make these on soft materials,” Prof Capasso assured the BBC.

The method can be used to scale to any size,he said.

“Once you have the foundry – you want a 12-inch lens? Feel free, you can make a 12-inch lens. There’s no limit.”

The character of the lens depends on the layout and composition of the pillars. The pillars are made out of titanium dioxide because it is cheap, transparent and interacts strongly with visible light.